This invention relates generally to air traps and more particularly to an air trap for use with apparatus for producing air bubbles in a body of water. Bubble producing devices have been used for many purposes, such as, for example, the aeration of lakes, the de-icing of channels and marinas, the oxidation and turnover of sewage lagoons and stagnant bodies of water, and the confining of water pollutants such as oil spills floating on the surface of a body of water. In systems of this type air under pressure is bubbled out through a pattern of openings arranged along one or more elongated conductors. In a typical system the conductors are constituted by weighted flexible hose and rest on the bottom of a body of water. However, they may be submerged to and held at an intermediate depth.
In the start-up of an ideal system, air supplied by the compressor displaces water in the conductor, forcing the water out through the openings. Air is first released from the opening nearest the compressor, with openings farther away from the compressor successively releasing air until the water in the conductor is completely displaced whereupon the system is in full operation. In many such systems, however, the air finds its path of least resistance in the several openings nearest the compressor. As a result, it often takes a great deal of time for water to be displaced throughout the entire length of a conductor. In some instances an equilibrium is reached in which the air-water interface within the conductor does not move at all, in which event the start-up time is infinitely long: it is impossible to release bubbles along the entire length of the conductor. The foregoing problems are especially apt to occur in systems wherein the depth of a conduit varies along its length in such a way that openings farther away from the compressor are deeper and thus subject to greater static pressure than openings nearer the compressor.
A related problem occurs where the openings in the conduit are check valves of distendable material, e.g. slits formed in the wall of a flexible plastic hose. By the time the water is pushed out through the openings at the far end of the hose system, the openings closer to the air supply which are already releasing air may have distended themselves to a condition in which they are larger than that which would be required for normal operation of the system. This excessive enlarging of the openings is caused because these openings temporarily handle the entire capacity of the compressor during start-up. The distended openings do not always resume their former shape when air reaches the far end of the conduit. As a result, there can be a waste of air at the location near the compressor while the openings more distant from the compressor may not get their rightful supply of air for uniform operation. The uniformity of air distribution is essential to the effectiveness of the operation of air bubbling systems and the problems described above have not yet been solved in the prior art.